#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

// .NET Compact Framework 1.0 has no support for reading assembly attributes
#if !NETCF

using System;

using log4net.Core;
#if !NETSTANDARD1_3
using log4net.Util;
#endif
using log4net.Plugin;

namespace log4net.Config
{
  /// <summary>
  /// Assembly level attribute that specifies a plugin to attach to 
  /// the repository.
  /// </summary>
  /// <remarks>
  /// <para>
  /// Specifies the type of a plugin to create and attach to the
  /// assembly's repository. The plugin type must implement the
  /// <see cref="IPlugin"/> interface.
  /// </para>
  /// </remarks>
  /// <author>Nicko Cadell</author>
  /// <author>Gert Driesen</author>
  [AttributeUsage(AttributeTargets.Assembly, AllowMultiple = true)]
  [Serializable]
  public sealed class PluginAttribute : Attribute, IPluginFactory
  {
    #region Public Instance Constructors

#if !NETSTANDARD1_3 // Excluded because GetCallingAssembly() is not available in CoreFX (https://github.com/dotnet/corefx/issues/2221).
    /// <summary>
    /// Initializes a new instance of the <see cref="PluginAttribute" /> class
    /// with the specified type.
    /// </summary>
    /// <param name="typeName">The type name of plugin to create.</param>
    /// <remarks>
    /// <para>
    /// Create the attribute with the plugin type specified.
    /// </para>
    /// <para>
    /// Where possible use the constructor that takes a <see cref="System.Type"/>.
    /// </para>
    /// </remarks>
    public PluginAttribute(string typeName)
    {
      m_typeName = typeName;
    }
#endif

    /// <summary>
    /// Initializes a new instance of the <see cref="PluginAttribute" /> class
    /// with the specified type.
    /// </summary>
    /// <param name="type">The type of plugin to create.</param>
    /// <remarks>
    /// <para>
    /// Create the attribute with the plugin type specified.
    /// </para>
    /// </remarks>
    public PluginAttribute(Type type)
    {
      m_type = type;
    }

    #endregion Public Instance Constructors

    #region Public Instance Properties

    /// <summary>
    /// Gets or sets the type for the plugin.
    /// </summary>
    /// <value>
    /// The type for the plugin.
    /// </value>
    /// <remarks>
    /// <para>
    /// The type for the plugin.
    /// </para>
    /// </remarks>
    public Type Type
    {
      get { return m_type; }
      set { m_type = value; }
    }

    /// <summary>
    /// Gets or sets the type name for the plugin.
    /// </summary>
    /// <value>
    /// The type name for the plugin.
    /// </value>
    /// <remarks>
    /// <para>
    /// The type name for the plugin.
    /// </para>
    /// <para>
    /// Where possible use the <see cref="Type"/> property instead.
    /// </para>
    /// </remarks>
    public string TypeName
    {
      get { return m_typeName; }
      set { m_typeName = value; }
    }

    #endregion Public Instance Properties

    #region Implementation of IPluginFactory

    /// <summary>
    /// Creates the plugin object defined by this attribute.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Creates the instance of the <see cref="IPlugin"/> object as 
    /// specified by this attribute.
    /// </para>
    /// </remarks>
    /// <returns>The plugin object.</returns>
    public IPlugin CreatePlugin()
    {
      Type pluginType = m_type;
#if !NETSTANDARD1_3
      if (m_type == null)
      {
        // Get the plugin object type from the string type name
        pluginType = SystemInfo.GetTypeFromString(m_typeName, true, true);
      }
#endif
      // Check that the type is a plugin
      if (!(typeof(IPlugin).IsAssignableFrom(pluginType)))
      {
        throw new LogException("Plugin type [" + pluginType.FullName + "] does not implement the log4net.IPlugin interface");
      }

      // Create an instance of the plugin using the default constructor
      IPlugin plugin = (IPlugin)Activator.CreateInstance(pluginType);

      return plugin;
    }

    #endregion Implementation of IPluginFactory

    #region Override implementation of Object

    /// <summary>
    /// Returns a representation of the properties of this object.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Overrides base class <see cref="M:Object.ToString()" /> method to 
    /// return a representation of the properties of this object.
    /// </para>
    /// </remarks>
    /// <returns>A representation of the properties of this object</returns>
    public override string ToString()
    {
      if (m_type != null)
      {
        return "PluginAttribute[Type=" + m_type.FullName + "]";
      }
      return "PluginAttribute[Type=" + m_typeName + "]";
    }

    #endregion Override implementation of Object

    #region Private Instance Fields

    private string m_typeName = null;
    private Type m_type = null;

    #endregion Private Instance Fields
  }
}

#endif // !NETCF